(1) Field of the Invention
The present invention generally relates to an ink jet recording head, a method for jetting an ink from such and a method for forming an ink jet recording head , and particularly to an ink jet recording head and a method for jetting an ink from such in which the ink can be accurately jetted from the ink jet recording head and a fine dot image can be formed on a recording sheet, and a method for forming an ink jet recording head in which the ink jet recording head can be accurately and easily formed at a low cost.
Conventionally, various methods and apparatus for forming an image on a recording sheet by jetting ink drops have been proposed.
U.S. Pat. Nos. 3,060,429, 3,596,275 and 3,416,153 disclose methods for forming a dot image in which ink dots are jetted by use of an electrostatic force. A method disclosed in U.S. Pat. No. 3,060,429 is often referred to as a Tele-type method, a method disclosed in U.S. Pat. No. 3,596,257 is often referred to as a Sweet method, and a method disclosed in U.S. Pat. No. 3,416,153 is often referred to as a Hertz method.
U.S. Pat. No. 3,747,120 discloses a method, often referred to as a Stemme method, in which the ink drops are jetted from orifices by use of a vibration mechanism such as a piezo-electric device.
Other methods for jetting ink drops by use of bubbles generated in the ink have also been proposed. For example, U.S. Pat. No. 4,580,148 discloses a method for jetting the ink drops in which, after a bubble has reached its maximum growth, the ink drop is jetted from the surface of the ink layer by a force which is generated when the bubble is quickly collapsed. In this method, when the bubble is quickly collapsed, small ink drops (mist) other than the primary ink drop can be easily generated. Thus, the quality of a dot image formed on the recording sheet easily deteriorates.
U.S. Pat. Nos. 4,558,333, 4,683,481, 4,794,410 and 4,882,595 disclose structures of an ink jet recording head in which ink drops are jetted therefrom by use of bubbles. In this type of the ink jet recording head, a heater element is surrounded by walls, and the bubble is generated in the ink on the heater element by heat of the heater element. The ink drop is jetted in a direction perpendicular to the heater element by the force of the growth of the bubble. However, in the ink jet recording head disclosed in the above references, an orifice plate having orifices is mounted on the walls so that each of the orifices faces the heater element. Each of these orifices can be obstructed by the ink whose viscosity is increased. In addition, the ink is supplied to inside the walls via flow ports which are formed between the walls. Thus, when the bubble grows, a part of the ink on the heater element flows toward the outside of the walls via the flow ports by the propulsion force of the bubble. That is, it is difficult to efficiently jet drops.